Random position shifts

I am running a tiled job on my OneFinity Woodworker running 1.0.9 release. The job size is 32 inches by 66 inches. The job was designed with VCarve Desktop Pro version 11.014. While running a tool the machine will just jump to a random new position and the program continues from this new incorrect position. I first thought my X axis stepper motor was slipping or skipping steps, but now realize I am losing position in both the X and Y axes.

Unfortunately, this is a job for pay and I cannot keep patching the PVC board with Bondo.

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Also could be EMI.

Ensure the controller and screen are on one circuit, and the router/vac are on separate circuits from these.

Ensure you have the router cord as far away from the motor driver wires as possible.


Thank you for your expert reply. I spent the afternoon checking all your recommendations but found nothing obvious. I then set Z an inch high and ran my program and noticed some noise during a X movement. I applied some light lube on the ball screw and the noise went away. Continued to dry run the machine for another hour.

I went back into VCarve and lowered all of my feed rates by 30%, and dry ran the machine again. No noises no problems.

Time to cut some material. First tool 1/4 clearance cut, went good. The second tool the finish vcarve went well 90% done and X bails. ESTOP! See photo.

But maybe most interesting of all, is after shutting the machine down and powering back up I notice the controller is now in Meteric mode. See photo. All of my work in done in good old Imperial. In fact after I did the recomended factory reset I noticed the jog speed buttons were showing in inches. My thoughts now is that maybe the controller power supply has gone bad…

Finally, I should have noted my experience with CNC… I am a Journeyman Machinist and first used CNC in the 1980’s. I have worked around these machines for most of my working life. In addition,

I was an Interior Communications Electrician in the Navy so I am familiar with electricity and electronics.

Again your thoughts and suggestions are most appreciated.

I do not use a trim router, but have an air cooled 3hp spindle and VFD with it’s own 220 volt home run line.

Did you change your jerk rate? I changed mine recently, then noticed missed steps on fast rapids. Went back into settings, and motor 3 went from 10,000 to 9,999.999 km/min^3. I set to 10,000. Went back into the screen to confirm it didn’t change. The problem went away.

While it’s unlikely this is causing your issue, I offer it on the off chance that it could help.

I usually notice this problem when I increase the Jerk settings. My advice, run stock settings.

Have you considered possible incoming noise from your electric utility?

I have multiple computers and IoT devices throughout the house, but none of those are showing any signs of power problems. While dry running the machine yesterday there were several times that my air compressor cycled on and off but the OneFinity did not seem to be affected. This was one of my first concerns and I ran the program for a while and had an event.

There seem to be some differing opinions on changing the Jerk Rate value. I would appreciate the input from OneFinity support before trying this one.

We’ve already gave input, post #1 and #2

I would look deeper into this. Because the noise temporarily disappeared after oiling (basically a band-aid fix), you may need to perform a proper deep-clean of the rails/screws.


So am I to assume that your first post is all the information you have to share on this issue and you are not going to give any input on why your controller switched from imperial to metric jog value inputs. This is NOT acceptable!

I would further like your view on the suggestion of the Jerk Value.

The first two posts were information as to what would cause shifts.

We never addressed switching from metric to imperial.
Two causes:
gcode is set to either metric or imperial
when using the probe, it always switches to metric, then stays that way. To get it back, simply switch from metric to imperial on the control screen. This will not have an affect on the cutting, as it’s simply a metric for what measurements you see on the control screen.
You may need to do this every time upon reboot.

Our suggestion for jerk value is to leave it as is from the factory. It’s a default value from the factory for a reason. Changing this value, while it may work for some, most or all, is not suggested by us, the manufacturer.


Thank you for answering my questions. I now have completed all of the suggestions in your first post and am running the machine Z high so that no material is being cut. The ball nuts were not very dirty but I have flushed then and they are all newly lubricated. Upon disassembly, I was supprised at the loose fit that the wipers have on the ball screw it would seem they could be redesigned and made far more effective. One new disturbing thing that I just noticed is that the X axis ball screw has .010 - .015 of run out at about X 25.000. This is not causing the jumps though since the last one was at about X 2.000.

I am shocked, at your explanation of the Imperial - Metric shift. First, my G code is definitely programmed in Imperial. To suggest that probing switches the machine to Metric and may fail to set it back is definitely a new problem with the controller and it’s code. By the way, I am not a OneFinity basher, I would buy another one in a heartbeat, although it would be the new 48 in X model. Your machine is the most solidly built machine on the market, successful machining is all dependedt to stability.

But from the very start, my opinion of the controller is that it is the weakest part of the machine. Not being able to adjust or tweek my RPM and Feed Rates makes your controller rank the worst one I’ve experienced. To later learn that it is programmed in HTML makes it a joke. But I know sacrifices were needed to keep the machine at it’s present price point.

Since my rambling here I heard 3 occurrences of jitter all on the X axis. The program runs for about 45 minutes. Upon completion and after the machine returned to home, I can clearly see that the X has moved and is almost back to hitting the left forward support. Please note that my X 0.000 Y 0.000 are only about .060 inch away from home since my workpiece is 32 inches, so it was very noticeable.

At this point I need to notify my customer that the machine is down and I am uncertain of the delay in delivery. I add this in an effort the OneFinity will give this issue priority.

I as always look forward to your response.

The runout seems odd… My assumption is after cleaning ball nuts it didn’t get put together as snuggly as it was before.

Are you doing any tight curves? Ie 0.25" diameter?

Is it always at a direction change?

It sounds like you are slipping somewhere. It may be worth having someone else try the file but unfortunately I am not able today.

As for the controller being html… It is not that basic/simple. Remember there are multiple components to it and the web interface usage makes it so you can do remote access as well. That is a perk to many of us. It also is not html directly coded… I suggest you go look at the code in bit bucket for some assurance.

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Hey John - I would agree with you that the controller is the weakest part of the Onefinity and to your point it is built to balance price and provide a solution that meets the needs of 95% of the users of this type of CNC. There is a group of users who want and would benefit from more advanced features like feed rate override as you mentioned.

That being said the issue you are experiencing is not normal of the controller. Most of the time when people have reported these types of issues it gets traced back to loose connections or EMI. If you have not already checked all of the stepper motor connections I would start there - look for any potential pin installation into the connector and pin fitment issues that may be present. After that EMI would be the next place to look - separate your “mains” voltage including the spindle cable from the stepper motor cables, in particular make sure they do not run parallel to each other, the high current 400hz feed to the spindle can cause all kinds of havoc on the stepper motor signal and potentially back into the controller. Potentially try running an air cut without the spindle running to see if that makes any difference.

The controller itself is not coded in HTML, only they presentation layer becomes HTML so it can be displayed on a web browser either locally or or over a network, this does not present a limitation in how the controller operates. The underlying code that drives the CNC motion is mostly C++ and Python


I would check grounding as well. I had some controller issues (not skipping steps) but they have pretty much gone away since I grounded the machine and the dust collection line. Well doing that I realized I had shorted wire in one of my Y rails. Onefinity promptly replaced and it and it has bene pretty smooth sailing since then.

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The only tight curves occur in the vcarving of letters. I have recently done much tighter curves (in letters).
I just captured a video of it happening on the X axis in a 5 inch rapid 45 degree move. Have not found how to attach it to a forum message yet.

@eJohn You might find this thread useful.